The invention relates to a hose coupling, in particular to a hose coupling including two coupling halves which take a coupling end position by relative rotation against each other about a coupling path of no more than 180°.
Known “Storz” couplings, which are used in particular in the field of firefighting, belong to an axially closing coupling type. Two identical coupling halves, which each consist of a hose connection and a cam ring rotatably arranged on the hose connection, are characteristic of Storz couplings. In this coupling type, at best only one half can alternatively be configured in one piece in the form of a stationary coupling.
The cam rings of the symmetrical coupling halves can be rotated with respect to the hose connections associated to each half, whereby it is possible to bring the cams of the cam rings into engagement in a bayonet lock manner with pitched shoulders of the cam ring of the respective other coupling half. The rotation of the cam rings produces an axial approach of the hose connections so that sealing rings arranged in the end faces thereof are pressed axially against each other without any mutual rotation. The angle of rotation necessary until the coupling end position is reached is principally determined by the number of cam/shoulder pairs, but is less than 180° in any case.
In a stationary coupling which is compatible with the hose coupling, the sealing ring, apart from the force transmitting elements, i.e. the cams and the shoulders, is also anchored on the one-piece coupling half and ensures, along with a rotatable cam ring of the counter-coupling half, the operational principle. A variant of the hose coupling is a cap fire hose coupling functioning as a pipe closure. In this case the hose connection is replaced by a blind cap formed in an identical manner on the coupling side and having a closed bottom.
Storz couplings are now used in many industrial fields where the transport of media other than water requires a protection against an unintended opening of the coupling connection. Since this coupling type belongs to the quick couplings, it is advantageous to have an automatic locking mechanism that can operate without additional manipulations during connection, and which cannot be forgotten, contrary to screw elements or wire brackets, for example. This is realized hitherto primarily in that a coupling collar behind a coupling shoulder obtains a milling groove through which a locking pawl movable about a rotation axis projects into a coupling path, whereby a decoupling is blocked. In most cases during the coupling operation, a cam of the counter-coupling half engages on an oblique plane of the pawl so that the pawl automatically gets out of the way, which in the opposite direction is prevented by a radial face. The weakening of the force transmitting region due to the milling groove can be accepted without concern, in particular when forged aluminum is used as coupling material, because it has great strength.
In the last years, the use of large-volume hoses having hose diameters of eight, ten and even twelve inches—at nominal pressures of 16 and more—has rendered corresponding coupling sizes necessary. Even if the pumping medium is water in most cases, the handling, which is not simple anymore, and the increased potential of danger of large masses under pressure in movable pipes require the arrangement of a locking mechanism. On the one hand, considering the tools and the number of pieces, the use of forging technology is too expensive. This is the reason why the couplings are produced in a casting process whereby in turn, the reduction in strength mentioned with respect to the configuration of the locking mechanism cannot be accepted in a hitherto used version. On the other hand, a large part of the periphery is not visible with such coupling sizes. For this reason, and also due to a plurality of ribs, the coupling state cannot be easily and immediately recognized, and misjudgements of supposed coupled connections cannot be excluded in spite of possible indicators. Here, a locking effect already starting during the coupling operation can prevent potential dangers.
It is an object of the invention to provide a hose coupling with a locking mechanism which, despite the transmission of large forces generally at high pressures, is not substantially reduced in cross-section by additional elements, which is simple to handle, and the effect of which occurs automatically and early during the coupling operation.